Spin-dyed polyacrylonitrile filaments



United States Patent 2 Claims. in. 260-41) This application is acont-inuation-in-part of US. application Serial No. 601,121, filed July31, 1956, now ab an doned.

The invention relates to spin-dyed polyacrylonitrile filaments and to aprocess of producing the same. More particularly the process consists indissolving in the spinning solution to be used for the production ofpolyacrylonitrile filaments a nigrosine base and spinning the solutionby conventional methods.

Nigrosine bases to be used in the present process are known under theclassical name Nigrosine Spirit Soluble (Colour Index, 2nd Edition, vol.3, No. 50415 and Farbstofitabellen by Schultz, 7th Edition, page 427)and are preferably produced by heating an arylamine such as aniline,aniline salts, and nitroor nitroso benzene in the presence of ironand/or iron salts at about 180 to 200 C. They are of more or lessindefinite structure.

The process is advantageously carried out by dissolving theafore-mentioned nigrosine bases into the vinyl polymer in dissolvedstate. The dyestuffs are preferably dissolved in the organic solventcommonly used for spinning of the polyacrylonitrile, such as indimetlhyl formamide. The solution thus obtained is then mixed with thesolution of the acrylonitrile polymer and then worked up into shapedarticles, particularly into filaments and fibres respectively.

The new process leads to dark spin-dyed polyacrylonitrile fibres whichexhibit excellent fastness properties,

3,232,904 Patented Feb. 1, 1966 especially very good fastness to lightand to rubbing. This result is most surprising because nigrosine basesdye polyacrylon-itrile shaped articles, such as fibres and filaments,only poor shades when applied from an aqueous dye-bath.

Example 15 kilograms of polyacrylonitrile and 0.150 kilogram ofNigrosine Spirit Soluble (Colour Index, 2nd Edition, No. 50415) aredissolved in kilograms of dimethylformamide and the solution is thenspun in conventional manner. A deep black spin-dyed fabric is thusobtained which exhibits excellent fastness proper-ties.

We claim:

1. A process for the manufacture of spin-dyed polyacrylonitrilefilaments which comprises dissolving in the spinning solution to be usedfor the production of polyacrylonitrile filaments a nigrosine spiritsoluble dyestuff and spinning the solution.

2. Spin-dyed polyacrylonitrile filaments obtained according to theprocess of claim 1.

References Cited by the Examiner UNITED STATES PATENTS 2,531,407 3/1950DAlelio 18-54 2,527,863 10/1950 Webb 26041 2,857,373 10/1958 Straley eta]. 855 2,941,970 6/1960 Craig 260-326 FOREIGN PATENTS 581,247 8/1959Canada.

OTHER REFERENCES Schultz, Farbstofftabellen, 7th Edition, page 427,1931.

MORRIS LIEBMAN, Primary Examiner.

DANIEL ARNOLD, WILLIAM H. SHORT,

ALEXANDER H. BRODMERKEL, Examiners.

1. A PROCESS FOR THE MANUFACTURE OF SPIN-DYED POLYACRYLONITRILEFILAMENTS WHICH COMPRISES DISSOLVING IN THE SPINNING SOLUTION TO BE USEDFOR THE PRODUCTION OF POLYACRYLONITRILE FILAMENTS A NIGROSINE SPIRITSOLULE DYESTUFF AND SPINNING THE SOLUTION.
 2. SPIN-DYEDPOLYACRYLONITRILE FILAMENTS OBTAINED ACCORDING TO THE PROCESS OF CLAIM1.